The RNAi process, found only in in eukaryotes, is initiate by

Options

A. ds RNA fragments
B. da DNA fragments
C. ss DNA fragments
D. ss RNA fragments

Answer

To solve the question regarding the initiation of the RNA interference (RNAi) process in eukaryotes, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding RNAi**:
- RNA interference (RNAi) is a biological process where RNA molecules inhibit gene expression or translation by neutralizing targeted mRNA molecules. This process is primarily found in eukaryotic organisms.

2. **Identifying the Initiator**:
- The initiation of RNAi is dependent on specific enzymes. The key enzyme responsible for initiating this process is called Dicer.

3. **Role of Dicer**:
- Dicer is an enzyme that cleaves long double-stranded RNA (dsRNA) into smaller fragments. This cleavage is essential for the RNAi pathway to function effectively.

4. **Formation of siRNA**:
- After Dicer cleaves the long dsRNA, it produces short double-stranded RNA fragments, typically around 21 nucleotides in length. These small fragments are known as small interfering RNAs (siRNAs).

5. **Conclusion**:
- Therefore, the RNAi process in eukaryotes is initiated by the enzyme Dicer, which cleaves long dsRNA into siRNA.

### Final Answer:
The RNAi process found only in eukaryotes is initiated by the enzyme Dicer.